LIFE AND LETTERS OF FA RAD A T. 313 
in our day. They arise from an imperfect acquaintance with 
the nature, present condition, and prospective vastness of 
the field of physical inquiry. The tendency of natural 
science doubtless is to bring all physical phenomena under 
the dominion of mechanical laws; to give them, in other 
words, mathematical expression. But our approach to 
this result is asymptotic; and for ages to come possibly 
for all the ages of the human race Nature will find room 
for both the philosophical experimenter and the mathe- 
matician. Faraday entered his protest against the fore- 
going statement by labeling his investigations " Experi- 
mental Researches in Electricity." They were completed 
in 1854, and three volumes of them have been published. 
For the sake of reference, he numbered every paragraph, 
the last number being 3,362. In 1859 he collected and 
published a fourth volume of papers, under the title, 
"Experimental Researches in Chemistry and Physics." 
Thus did this apostle of experiment illustrate its power, 
and magnify his office. 
The second volume of the Researches embraces memoirs 
on the Electricity o'f the Gymnotus; on the Source of 
Power in the Voltaic Pile; on the Electricity evolved by the 
Friction of Water and Steam, in which the phenomena and 
principles of Sir William Armstrong's Hydro-electric ma- 
chineare described and developed; a paper on Magnetic Rota- 
tions, and Faraday's letters in relation to the controversy 
it aroused. The contribution of most permanent value 
here, is that on the Source of Power in the Voltaic Pile. 
By it the Contact Theory, pure and simple, was totally 
overthrown, and the necessity of chemical action to the 
maintenance of the current demonstrated. 
The third volume of the Researches opens with a memoir 
entitled "The Magnetization of Light," and the "Illu- 
mination of Magnetic Lines of Force." It is difficult even 
now to affix a definite meaning to this title; but the dis- 
covery of the rotation of the plane of polarization, which it 
announced, seems pregnant with great results. The writ- 
ings of William Thomson on the theoretic aspects of the 
discovery; the excellent electro-dynamic measurements of 
Wilhelm Weber, which are models of experimental com- 
pleteness and skill; Weber's labors in conjunction with his 
lamented friend Kohlrausch above all, the researches of 
Clerk Maxwell on the Electro-magnetic Theory of Light > 
